Well I started out ten or so years ago with a .375H&H Brno 602, which was a lovely gun. I sold it but couldn't completely kick the habit, so I recently bought a .416 Rigby CZ550. Before I've even mastered the art of shooting that well I'm trying to figure out how I can get myself a .5something double?! I was told that a true big bore had to start with at least .4, but I'm not so sure. I think .5 looks better!